Anthony Delaney left court yesterday clutching a bag full of belongings. He had escaped prison, but reaped the wrath of the judge at Lewes crown court for breaching an asbo which banned him from Gatwick airport where he had lived for more than three years.

The court heard that the 43-year-old chef did not suffer from mental health problems, was neither a drug nor alcohol addict and did not cause any problems. Instead, he is said to have told his barrister that he was happier staying there because he was "clean, dry and warm".

"You are a fully qualified head chef and I cannot understand why you haven't been able to find a job for four years when the south coast is bustling with food outlets," Judge Richard Hayward told Delaney, deferring sentence until later this year.

Delaney's story - reminiscent of the film The Terminal in which a man played by Tom Hanks makes JFK airport his home - is not unique. Three other people have received asbos for repeatedly using Gatwick as their home, and up to 30 make makeshift beds in the airport each night, according to charities. An outreach project run by Broadway identified 26 homeless people spending nights at Heathrow in just two sessions and the charity says further work is likely to find more rough sleepers.

BAA said it did not recognise the figure of 30 people sleeping at Gatwick but could not estimate what the number was because anyone found doing so would be moved on.

Jason, a 30-year-old Zimbabwean who spent his time at Heathrow and Gatwick between 2003 and 2007 said: "I recently took the time to see The Terminal and I think he had a pretty cushy kind of a deal. It's nothing like that. You're constantly watching your back, trying not to step on anybody's toes, and at the same time making sure you've got everything you need to get by. I laugh now but at the time it was a matter of survival."

Campaigners say the phenomenon of rough sleepers who gravitate towards the warmth and safety offered by airports is part of the problem of "hidden homelessness" - people who are not counted in official figures because they are not sleeping on the streets.

Jason, who was jailed for nine and a half weeks last year for breaching his asbo and is now in a hostel, started sleeping rough in 2003 after quitting his job at a racing stables in Oxfordshire and getting heavily into debt. "I had nowhere to go," he said. "It was pretty cold and wet at the time and Heathrow was the first place that came to mind." He spent about five months there before his face became too well known with the police and someone suggested he might have better luck at Gatwick.

After that he would shuttle between the two every few weeks.

The life of an airport rough sleeper is a complex one, said Peter Mansfield-Clark, director of the nearby Crawley Open House which works with the homeless. "Once people are used to it they take a rucksack with them with a change of clothes. They go into one of the toilet areas and they'll have a wash, a shave if need be, make themselves look tidy and put the clothes on. They'll quite often be travel-type clothes, as if they're just waiting to go off somewhere or they've just come back. If you look the part, you've a chance of being able to sleep without anyone disturbing you." Jason's days started at 5am, roused by the public announcement systems and influx of new passengers.

Then he would try to make himself scarce in such places as in the prayer room at Heathrow or by a small lake outside Gatwick. He would scour car parks for dropped change and try to grab a shower when the bathrooms were less busy. On two occasions he got a job and moved away but returned when they fell through. "When I first started I was sleeping on the benches on the public areas but the police come round every couple of hours," he said. "So I started looking for more secluded areas where the public and security aren't going to keep asking questions. Sometimes you'd be lucky enough to slip into a hotel and crash in the linen cupboard or something."

At their peak, he believes there could have been 50 rough sleepers at Heathrow, but although they might recognise each other contact was kept to a minimum. "A lot of people in that position are almost afraid to admit this is what they've come to. Maybe if you saw them over and over again in the showers or the prayer rooms you might greet them and see how they are but that's about it. We weren't on first-name terms."

Visit Gatwick by night and there are plenty of people sprawled across the lounge chairs trying to sleep. Most are waiting for flights, but there are small clues that give away those who are not.

The young man who counted his change with unusual care at McDonald's in the north terminal one night this week had no suitcase. Just after midnight he was woken by a police officer who escorted him to the train station.

Jason says he would return to the airports if necessary, even though the experience is stressful. "It's not like when you have a home and you can close the door and put your feet up."

Off the radar

The charity Crisis estimates there are up to 400,000 people considered "hidden homeless". They do not qualify to get support, such as emergency accommodation, but often sleep in squats or stay with friends or relatives. Others may bed down in sheds and outbuildings, airports and bus and train stations, or try to sleep on night buses. "Rough sleeping might be the most visible sort of homelessness but it's not the only sort," said Duncan Shrubsole, head of policy and research.